Extended area of sputter deposited n-type and p-type thermoelectric legs in a flexible thin-film based thermoelectric device

ABSTRACT

A method includes forming a thin-film based thermoelectric module by sputter depositing pairs of N-type and P-type thermoelectric legs electrically in contact with one another on corresponding electrically conductive pads on a flexible substrate having a dimensional thickness less than or equal to 25 μm, with the legs having extended areas compared to the corresponding electrically conductive pads, and rendering the formed thin-film based thermoelectric module flexible and less than or equal to 100 μm in dimensional thickness based on choices of fabrication processes. The method also includes encapsulating the formed thin-film based thermoelectric module with an elastomer to render the flexibility thereto. The elastomer encapsulation has a dimensional thickness less than or equal to 15 μm, and the flexibility enables an array of thin-film based thermoelectric modules to be completely wrappable and bendable around a system element from which the array is configured to derive thermoelectric power.

CLAIM OF PRIORITY

This application is a continuation-in-part application of co-pendingU.S. application Ser. No. 15/869,017 titled FLEXIBLE ENCAPSULATION OF AFLEXIBLE THIN-FILM BASED THERMOELECTRIC DEVICE WITH SPUTTER DEPOSITEDLAYER OF N-TYPE AND P-TYPE THERMOELECTRIC LEGS filed on Jan. 11, 2018,co-pending U.S. application Ser. No. 15/808,902 titled FLEXIBLETHIN-FILM BASED THERMOELECTRIC DEVICE WITH SPUTTER DEPOSITED LAYER OFN-TYPE AND P-TYPE THERMOELECTRIC LEGS filed on Nov. 10, 2017, co-pendingU.S. application Ser. No. 14/564,072 titled VOLTAGE GENERATION ACROSSTEMPERATURE DIFFERENTIALS THROUGH A THERMOELECTRIC LAYER COMPOSITE filedon Dec. 8, 2014, which is a conversion application of U.S. ProvisionalApplication No. 61/912,561 also titled VOLTAGE GENERATION ACROSSTEMPERATURE DIFFERENTIALS THROUGH A THERMOELECTRIC LAYER COMPOSITE filedon Dec. 6, 2013, co-pending U.S. application Ser. No. 14/711,810 titledENERGY HARVESTING FOR WEARABLE TECHNOLOGY THROUGH A THIN FLEXIBLETHERMOELECTRIC DEVICE filed on May 14, 2015, and co-pending U.S.application Ser. No. 15/368,683 titled PIN COUPLING BASED THERMOELECTRICDEVICE filed on Dec. 5, 2016. The contents of the aforementionedapplications are incorporated by reference in entirety thereof.

FIELD OF TECHNOLOGY

This disclosure relates generally to thermoelectric devices and, moreparticularly, to extended area of sputter deposited N-type and P-typethermoelectric legs in a flexible thin-film based thermoelectric device.

BACKGROUND

A thermoelectric device may be formed from alternating N and Pelements/legs made of semiconducting material on a rigid substrate(e.g., alumina) joined on a top thereof to another rigid substrate/plate(e.g., again, alumina). In a typical bulk thermoelectric module/device,N-type thermoelectric legs and P-type thermoelectric legs may bebookended by top and bottom metal traces. Because of the typical longlength of said N-type thermoelectric legs and P-type thermoelectriclegs, there is no shunting during soldering of the metal traces.

However, as the height of the N-type thermoelectric legs and the P-typethermoelectric legs reduce in thin-film based thermoelectric devices,the top metal trace(s) may shunt the bottom metal trace(s) duringdeposition thereof.

SUMMARY

Disclosed are methods, a device and/or a system of extended area ofsputter deposited N-type and P-type thermoelectric legs in a flexiblethin-film based thermoelectric device.

In one aspect, a method of a thin-film based thermoelectric moduleincludes forming the thin-film based thermoelectric module by sputterdepositing pairs of N-type thermoelectric legs and P-type thermoelectriclegs electrically in contact with one another on correspondingelectrically conductive pads on a flexible substrate such that an areaof each sputter deposited N-type thermoelectric leg and another area ofeach sputter deposited P-type thermoelectric leg is more than an area ofthe corresponding electrically conductive pad to allow for extensionthereof outside the corresponding electrically conductive pad. Theflexible substrate is an aluminum (Al) foil, a sheet of paper, teflon,plastic, a single-sided copper (Cu) clad laminate sheet, or adouble-sided Cu clad laminate sheet, and the flexible substrate has adimensional thickness less than or equal to 25 μm.

The method also includes rendering the formed thin-film basedthermoelectric module flexible and less than or equal to 100 μm indimensional thickness based on choices of fabrication processes withrespect to layers of the formed thin-film based thermoelectric moduleincluding the sputter deposited N-type thermoelectric legs and theP-type thermoelectric legs, and encapsulating the formed thin-film basedthermoelectric module with an elastomer to render the flexibilitythereto. The elastomer encapsulation has a dimensional thickness lessthan or equal to 15 μm, and the flexibility enables an array ofthin-film based thermoelectric modules, each of which is equivalent tothe thin-film based thermoelectric module formed on the flexiblesubstrate with the elastomer encapsulation, to be completely wrappableand bendable around a system element from which the array of thethin-film based thermoelectric modules is configured to derivethermoelectric power.

A layer of the formed thin-film based thermoelectric module includingthe sputter deposited N-type thermoelectric legs and the P-typethermoelectric legs has a dimensional thickness less than or equal to 25μm.

In another aspect, a method of a thin-film based thermoelectric moduleincludes forming the thin-film based thermoelectric module by sputterdepositing pairs of N-type thermoelectric legs and P-type thermoelectriclegs electrically in contact with one another on correspondingelectrically conductive pads on a flexible substrate such that an areaof each sputter deposited N-type thermoelectric leg and another area ofeach sputter deposited P-type thermoelectric leg is more than an area ofthe corresponding electrically conductive pad to allow for extensionthereof outside the corresponding electrically conductive pad. Theflexible substrate is an Al foil, a sheet of paper, teflon, plastic, asingle-sided Cu clad laminate sheet, or a double-sided Cu clad laminatesheet, and the flexible substrate has a dimensional thickness less thanor equal to 25 μm.

The method also includes rendering the formed thin-film basedthermoelectric module flexible and less than or equal to 100 μm indimensional thickness based on choices of fabrication processes withrespect to layers of the formed thin-film based thermoelectric moduleincluding the sputter deposited N-type thermoelectric legs and theP-type thermoelectric legs. A layer of the formed thin-film basedthermoelectric module including the sputter deposited N-typethermoelectric legs and the P-type thermoelectric legs has a dimensionalthickness less than or equal to 25 μm.

Further, the method includes encapsulating the formed thin-film basedthermoelectric module with an elastomer to render the flexibilitythereto, and wrapping and bending an array of thin-film basedthermoelectric modules, each of which is equivalent to the thin-filmbased thermoelectric module formed on the flexible substrate with theelastomer encapsulation, completely around a system element from whichthe array of the thin-film based thermoelectric modules is configured toderive thermoelectric power in accordance with the flexibility thereof.The elastomer encapsulation has a dimensional thickness less than orequal to 15 μm.

In yet another aspect, a method of a thin-film based thermoelectricdevice includes forming the thin-film based thermoelectric device out ofan array of thermoelectric modules, each of which is less than or equalto 100 μm in dimensional thickness and is formed by sputter depositingpairs of N-type thermoelectric legs and P-type thermoelectric legselectrically in contact with one another on corresponding electricallyconductive pads on a flexible substrate such that an area of eachsputter deposited N-type thermoelectric leg and another area of eachsputter deposited P-type thermoelectric leg is more than an area of thecorresponding electrically conductive pad to allow for extension thereofoutside the corresponding electrically conductive pad. The flexiblesubstrate is an Al foil, a sheet of paper, teflon, plastic, asingle-sided Cu clad laminate sheet, or a double-sided Cu clad laminatesheet, and the flexible substrate has a dimensional thickness less thanor equal to 25 μm.

A layer of the each thermoelectric module including the sputterdeposited N-type thermoelectric legs and the P-type thermoelectric legshas a dimensional thickness less than or equal to 25 μm. The method alsoincludes rendering the formed thin-film based thermoelectric deviceflexible based on choices of fabrication processes with respect tolayers of the each thermoelectric module including the sputter depositedN-type thermoelectric legs and the P-type thermoelectric legs, andencapsulating the each thermoelectric module of the formed thin-filmbased thermoelectric device with an elastomer to render the flexibilitythereto. The elastomer encapsulation has a dimensional thickness lessthan or equal to 15 μm, and the flexibility enables the formed thin-filmbased thermoelectric device to be completely wrappable and bendablearound a system element from which the formed thin-film basedthermoelectric device is configured to derive thermoelectric power.

Other features will be apparent from the accompanying drawings and fromthe detailed description that follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments of this invention are illustrated by way of example andnot limitation in the figures of the accompanying drawings, in whichlike references indicate similar elements and in which:

FIG. 1 is a schematic view of a thermoelectric device.

FIG. 2 is a schematic view of an example thermoelectric device withalternating P and N elements.

FIG. 3 is a top schematic view of a thermoelectric device component,according to one or more embodiments.

FIG. 4 is a process flow diagram detailing the operations involved inrealizing a patterned flexible substrate of a thermoelectric device asper a design pattern, according to one or more embodiments.

FIG. 5 is a schematic view of the patterned flexible substrate of FIG.4, according to one or more embodiments.

FIG. 6 is a schematic view of the patterned flexible substrate of FIG. 4with N-type thermoelectric legs, P-type thermoelectric legs, a barrierlayer and conductive interconnects, according to one or moreembodiments.

FIG. 7 is a process flow diagram detailing the operations involved insputter deposition of the N-type thermoelectric legs of FIG. 6 on thepatterned flexible substrate (or, a seed metal layer) of FIG. 5,according to one or more embodiments.

FIG. 8 is a process flow diagram detailing the operations involved indeposition of the barrier layer of FIG. 6 on top of the sputterdeposited pairs of P-type thermoelectric legs and the N-typethermoelectric legs of FIG. 6 and forming the conductive interconnectsof FIG. 6 on top of the barrier layer, according to one or moreembodiments.

FIG. 9 is a process flow diagram detailing the operations involved inencapsulating the thermoelectric device of FIG. 4 and FIG. 6, accordingto one or more embodiments.

FIG. 10 is a schematic view of a flexible thermoelectric device embeddedwithin a watch strap of a watch completely wrappable around a wrist of ahuman being.

FIG. 11 is a schematic view of a flexible thermoelectric device wrappedaround a heat pipe.

FIG. 12 is a schematic view of a thermoelectric device with elastomerencapsulation, according to one or more embodiments.

FIG. 13 is a schematic view of deposition of a barrier film prior toapplication of an elastomer to encapsulate the thermoelectric device ofFIG. 12, according to one or more embodiments.

FIG. 14 is a schematic view of flexibility and bendability of an examplethermoelectric device in accordance with the embodiment of FIG. 12.

FIG. 15 is a schematic view of an increased/extended area of an N-typethermoelectric leg and another increased/extended area of a P-typethermoelectric leg compared to an area of corresponding electricallyconductive pads to ensure no shunting during deposition of conductiveinterconnects in the thermoelectric devices of FIGS. 6 and 8-14,according to one or more embodiments.

FIG. 16 is a process flow diagram detailing the operations involved inrealizing a flexible thin-film based thermoelectric module with sputterdeposited N-type and P-type thermoelectric legs having extended areasthereof, according to one or more embodiments.

Other features of the present embodiments will be apparent from theaccompanying drawings and from the detailed description that follows.

DETAILED DESCRIPTION

Example embodiments, as described below, may be used to provide methods,a device and/or a system of extended area of sputter deposited N-typeand P-type thermoelectric legs in a flexible thin-film basedthermoelectric device. Although the present embodiments have beendescribed with reference to specific example embodiments, it will beevident that various modifications and changes may be made to theseembodiments without departing from the broader spirit and scope of thevarious embodiments.

FIG. 1 shows a thermoelectric device 100. Thermoelectric device 100 mayinclude different metals, metal 1 102 and metal 2 104, forming a closedcircuit. Here, a temperature difference between junctions of saiddissimilar metals leads to energy levels of electrons therein shifted ina dissimilar manner. This results in a potential/voltage differencebetween the warmer (e.g., warmer junction 106) of the junctions and thecolder (e.g., colder junction 108) of the junctions. The aforementionedconversion of heat into electricity at junctions of dissimilar metals isknown as Seebeck effect.

The most common thermoelectric devices in the market may utilizealternative P and N type legs/pellets/elements made of semiconductingmaterials. As heat is applied to one end of a thermoelectric devicebased on P and N type elements, charge carriers thereof may be releasedinto the conduction band. Electron (charge carrier) flow in the N typeelement may contribute to a current flowing from the end (hot end) wherethe heat is applied to the other end (cold end). Hole (charge carrier)flow in the P type element may contribute to a current flowing from theother end (cold end) to the end (hot end) where the heat is applied.Here, heat may be removed from the cold end to prevent equalization ofcharge carrier distribution in the semiconductor materials due tomigration thereof.

In order to generate voltage at a meaningful level to facilitate one ormore application(s), typical thermoelectric devices may utilizealternating P and N type elements (legs/pellets) electrically coupled inseries (and thermally coupled in parallel) with one another, as shown inFIG. 2. FIG. 2 shows an example thermoelectric device 200 includingthree alternating P and N type elements 202 ₁₋₃. The hot end (e.g., hotend 204) where heat is applied and the cold end (e.g., cold end 206) arealso shown in FIG. 2.

Typical thermoelectric devices (e.g., thermoelectric device 200) may belimited in application thereof because of rigidity, bulkiness and highcosts (>$20/watt) associated therewith. Also, these devices may operateat high temperatures using active cooling. Exemplary embodimentsdiscussed herein provide for a thermoelectric platform (e.g., enabledvia roll-to-roll sputtering on a flexible substrate (e.g., plastic))that offers a large scale, commercially viable, high performance, easyintegration and inexpensive (<20 cents/watt) route to flexiblethermoelectrics.

In accordance with the exemplary embodiments, P and N thermoelectriclegs may be deposited on a flexible substrate (e.g., plastic) using aroll-to-roll process that offers scalability and cost savings associatedwith the N and P materials. In a typical solution, bulk legs may have aheight in millimeters (mm) and an area in mm². In contrast, N and P bulklegs described in the exemplary embodiments discussed herein may have aheight in microns (μm) and an area in the μm² to mm² range.

Examples of flexible substrates may include but are not limited toaluminum (Al) foil, a sheet of paper, teflon, plastic and asingle/double-sided copper (Cu) clad laminate sheet. As will bediscussed below, exemplary embodiments involve processes formanufacturing/fabrication of thermoelectric devices/modules that enableflexibility thereof not only in terms of substrates but also in terms ofthin films/thermoelectric legs/interconnects/packaging. Preferably,exemplary embodiments provide for thermoelectric devices/modulescompletely wrappable and bendable around other devices utilized inspecific applications, as will be discussed below. Further, exemplaryembodiments provide for manufactured/fabricated thermoelectricdevices/modules that are each less than or equal to 100 μm indimensional thickness. Although exemplary embodiments discussthermoelectric devices in general, it is clear that the aforementionedthermoelectric devices are preferably thin-film based thermoelectricdevices.

FIG. 3 shows a top view of a thermoelectric device component 300,according to one or more embodiments. Here, in one or more embodiments,a number of sets of N and P legs (e.g., sets 302 _(1-M) including N legs304 _(1-M) and P legs 306 _(1-M) therein) may be deposited on asubstrate 350 (e.g., plastic, Cu clad laminate sheet) using aroll-to-roll process discussed above. FIG. 3 also shows a conductivematerial 308 _(1-M) contacting both a set 302 _(1-M) and substrate 350,according to one or more embodiments; an N leg 304 _(1-M) and a P leg306 _(1-M) form a set 302 _(1-M), in which N leg 304 _(1-M) and P leg306 _(1-M) electrically contact each other through conductive material308 _(1-M). Terminals 370 and 372 may be electrically conductive leadsto measure the potential difference generated by a thermoelectric deviceincluding thermoelectric device component 300.

Exemplary thermoelectric devices discussed herein may find utility insolar and solar thermal applications. As discussed above, traditionalthermoelectric devices may have a size limitation and may not scale to alarger area. For example, a typical solar panel may have an area in thesquare meter (m²) range and the traditional thermoelectric device mayhave an area in the square inch range. A thermoelectric device inaccordance with the exemplary embodiments may be of varying sizes and/ordimensions ranging from a few mm² to a few m².

Additionally, exemplary thermoelectric devices may find use in lowtemperature applications such as harvesting body heat in a wearabledevice, automotive devices/components and Internet of Things (IoT).Entities (e.g., companies, start-ups, individuals, conglomerates) maypossess expertise to design and/or develop devices that requirethermoelectric modules, but may not possess expertise in the fabricationand packaging of said thermoelectric modules. Alternately, even thoughthe entities may possess the requisite expertise in the fabrication andpackaging of the thermoelectric modules, the entities may not possess acomparative advantage with respect to the aforementioned processes.

In one scenario, an entity may create or possess a design pattern for athermoelectric device. Said design pattern may be communicated toanother entity associated with a thermoelectric platform to be tangiblyrealized as a thermoelectric device. It could also be envisioned thatthe another entity may provide training with regard to the fabricationprocesses to the one entity or outsource aspects of the fabricationprocesses to a third-party. Further, the entire set of processesinvolving Intellectual Property (IP) generation andmanufacturing/fabrication of the thermoelectric device may be handled bya single entity. Last but not the least, the entity may generate the IPinvolving manufacturing/fabrication of the thermoelectric device andoutsource the actual manufacturing/fabrication processes to the anotherentity.

All possible combinations of entities and third-parties are within thescope of the exemplary embodiments discussed herein.

FIG. 4 shows the operations involved in realizing a patterned flexiblesubstrate (e.g., patterned flexible substrate 504 shown in FIG. 5) of athermoelectric device 400 as per a design pattern (e.g., design pattern502 shown in FIG. 5), according to one or more embodiments. In one ormore embodiments, operation 402 may involve choosing a flexiblesubstrate (e.g., substrate 350) onto which, in operation 404, designpattern 502 may be printed (e.g., through inkjet printing, direct write,screen printing) and etched onto the flexible substrate. In one or moreembodiments, a dimensional thickness of substrate 350 may be less thanor equal to 25 μm.

Etching, as defined above, may refer to the process of removing (e.g.,chemically) unwanted metal (say, Cu) from the patterned flexiblesubstrate. In one example embodiment, a mask or a resist may be placedon portions of the patterned flexible substrate corresponding toportions of the metal that are to remain after the etch. Here, in one ormore embodiments, the portions of the metal that remain on the patternedflexible substrate may be electrically conductive pads, electricallyconductive leads and terminals formed on a surface of the patternedflexible substrate. FIG. 5 shows a patterned flexible substrate 504including a number of electrically conductive pads 506 _(1-N) formedthereon. Each electrically conductive pad 506 _(1-N) may be a flat areaof the metal that enables an electrical connection.

Also, FIG. 5 shows a majority set of the electrically conductive pads506 _(1-N) as including pairs 510 _(1-P) of electrically conductive pads506 _(1-N) in which one electrically conductive pad 506 _(1-N) may beelectrically paired to another electrically conductive pad 506 _(1-N)through an electrically conductive lead 512 _(1-P) also formed onpatterned flexible substrate 504; terminals 520 ₁₋₂ (e.g., analogous toterminals 370 and 372) may also be electrically conductive leads tomeasure the potential difference generated by the thermoelectricdevice/module fabricated based on design pattern 502. The aforementionedpotential difference may be generated based on heat (or, cold) appliedat an end of the thermoelectric device/module.

It should be noted that the configurations of the electricallyconductive pads 506 _(1-N), electrically conductive leads 512 _(1-P) andterminals 520 ₁₋₂ shown in FIG. 5 are merely for example purposes, andthat other example configurations are within the scope of the exemplaryembodiments discussed herein. It should also be noted that patternedflexible substrate 504 may be formed based on design pattern 502 inaccordance with the printing and etching discussed above.

Example etching solutions employed may include but are not limited toferric chloride and ammonium persulphate. Referring back to FIG. 4,operation 406 may involve cleaning the printed and etched flexiblesubstrate. For example, acetone, hydrogen peroxide or alcohol may beemployed therefor. Other forms of cleaning are within the scope of theexemplary embodiments discussed herein. In one or more embodiments, theaforementioned processes discussed in FIG. 4 may result in a dimensionalthickness of electrically conductive pads 506 _(1-N), electricallyconductive leads 512 _(1-P) and terminals 520 ₁₋₂ being less than orequal to 18 μm.

The metal (e.g., Cu) finishes on the surface of patterned flexiblesubstrate 504 may oxidize over time if left unprotected. As a result, inone or embodiments, operation 408 may involve additionallyelectrodepositing a seed metal layer 550 including Chromium (Cr), Nickel(Ni) and/or Gold (Au) directly on top of the metal portions (e.g.,electrically conductive pads 506 _(1-N), electrically conductive leads512 _(1-P), terminals 520 ₁₋₂) of patterned flexible substrate 504following the printing, etching and cleaning. In one or moreembodiments, a dimensional thickness of seed metal layer 550 may be lessthan or equal to 5 μm.

In one example embodiment, surface finishing may be employed toelectrodeposit seed metal layer 550; the aforementioned surfacefinishing may involve Electroless Nickel Immersion Gold (ENIG)finishing. Here, a coating of two layers of metal may be provided overthe metal (e.g., Cu) portions of patterned flexible substrate 504 by wayof Au being plated over Ni. Ni may be the barrier layer between Cu andAu. Au may protect Ni from oxidization and may provide for low contactresistance. Other forms of surface finishing/electrodeposition may bewithin the scope of the exemplary embodiments discussed herein. Itshould be noted that seed metal layer 550 may facilitate contact ofsputter deposited N-type thermoelectric legs (to be discussed below) andP-type thermoelectric legs (to be discussed below) thereto.

In one or more embodiments, operation 410 may then involve cleaningpatterned flexible substrate 504 following the electrodeposition. FIG. 6shows an N-type thermoelectric leg 602 _(1-P) and a P-typethermoelectric leg 604 _(1-P) formed on each pair 510 _(1-P) ofelectrically conductive pads 506 _(1-N), according to one or moreembodiments. In one or more embodiments, the aforementioned N-typethermoelectric legs 602 _(1-P) and P-type thermoelectric legs 604 _(1-P)may be formed on the surface finished patterned flexible substrate 504(note: in FIG. 6, seed layer 550 is shown as surface finishing overelectrically conductive pads 506 _(1-N)/leads 512 _(1-P); terminals 520₁₋₂ have been omitted for the sake of clarity) of FIG. 5 through sputterdeposition.

FIG. 7 details the operations involved in sputter deposition of N-typethermoelectric legs 602 _(1-P) on the surface finished patternedflexible substrate 504 (or, seed metal layer 550) of FIG. 5, accordingto one or more embodiments. In one or more embodiments, theaforementioned process may involve a photomask 650 (shown in FIG. 6) onwhich patterns corresponding/complementary to the N-type thermoelectriclegs 602 _(1-P) may be generated. In one or more embodiments, aphotoresist 670 (shown in FIG. 6) may be applied on the surface finishedpatterned flexible substrate 504, and photomask 650 placed thereon. Inone or more embodiments, operation 702 may involve sputter coating(e.g., through magnetron sputtering) of the surface finished patternedflexible substrate 504 (or, seed metal layer 550) with an N-typethermoelectric material corresponding to N-type thermoelectric legs 602_(1-P), aided by the use of photomask 650. The photoresist 670/photomask650 functions are well understood to one skilled in the art; detaileddiscussion associated therewith has been skipped for the sake ofconvenience and brevity.

In one or more embodiments, operation 704 may involve stripping (e.g.,using solvents such as dimethyl sulfoxide or alkaline solutions) ofphotoresist 670 and etching of unwanted material on patterned flexiblesubstrate 504 with sputter deposited N-type thermoelectric legs 602_(1-P). In one or more embodiments, operation 706 may involve cleaningthe patterned flexible substrate 504 with the sputter deposited N-typethermoelectric legs 602 _(1-P); the cleaning process may be similar tothe discussion with regard to FIG. 4.

In one or more embodiments, operation 708 may then involve annealing thepatterned flexible substrate 504 with the sputter deposited N-typethermoelectric legs 602 _(1-P); the annealing process may be conducted(e.g., in air or vacuum) at 175° C. for 4 hours. In one or moreembodiments, the annealing process may remove internal stresses and maycontribute stability of the sputter deposited N-type thermoelectric legs602 _(1-P). In one or more embodiments, a dimensional thickness of thesputter deposited N-type thermoelectric legs 602 _(1-P) may be less thanor equal to 25 μm.

It should be noted that P-type thermoelectric legs 604 _(1-P) may alsobe sputter deposited on the surface finished pattern flexible substrate504. The operations associated therewith are analogous to those relatedto the sputter deposition of N-type thermoelectric legs 602 _(1-P).Obviously, photomask 650 may have patterns corresponding/complementaryto the P-type thermoelectric legs 604 _(1-P) generated thereon. Detaileddiscussion associated with the sputter deposition of P-typethermoelectric legs 604 _(1-P) has been skipped for the sake ofconvenience; it should be noted that a dimensional thickness of thesputter deposited P-type thermoelectric legs 604 _(1-P) may also be lessthan or equal to 25 μm.

It should be noted that the sputter deposition of P-type thermoelectriclegs 604 _(1-P) on the surface finished patterned flexible substrate 504may be performed after the sputter deposition of N-type thermoelectriclegs 602 _(1-P) thereon or vice versa. Also, it should be noted thatvarious feasible forms of sputter deposition are within the scope of theexemplary embodiments discussed herein. In one or more embodiments, thesputter deposited P-type thermoelectric legs 604 _(1-P) and/or N-typethermoelectric legs 602 _(1-P) may include a material chosen from oneof: Bismuth Telluride (Bi₂Te₃), Bismuth Selenide (Bi₂Se₃), AntimonyTelluride (Sb₂Te₃), Lead Telluride (PbTe), Silicides, Skutterudites andOxides.

FIG. 8 details operations involved in deposition of a barrier layer 672(refer to FIG. 6) on top of the sputter deposited pairs of P-typethermoelectric legs 604 _(1-P) and N-type thermoelectric legs 602 _(1-P)and forming conductive interconnects 696 on top of barrier layer 672,according to one or more embodiments.

In one or more embodiments, operation 802 may involve sputter depositingbarrier layer 672 (e.g., film) on top of the sputter deposited pairs ofthe P-type thermoelectric legs 604 _(1-P) and the N-type thermoelectricleg 602 _(1-P) discussed above. In one or more embodiments, barrierlayer 672 may be electrically conductive and may have a higher meltingtemperature than the thermoelectric material forming the P-typethermoelectric legs 604 _(1-P) and the N-type thermoelectric legs 602_(1-P). In one or more embodiments, barrier layer 672 may preventcorruption (e.g., through diffusion, sublimation) of one layer (e.g.,the thermoelectric layer including the P-type thermoelectric legs 604_(1-P) and the N-type thermoelectric legs 602 _(1-P)) by another layer.An example material employed as barrier layer 672 may include but is notlimited to Cr, Ni or Au. Further, in one or more embodiments, barrierlayer 672 may further aid metallization contact therewith (e.g., withconductive interconnects 696).

In one or more embodiments, a dimensional thickness of barrier layer 672may be less than or equal to 5 μm. It is obvious that another photomask(not shown) analogous to photomask 650 may be employed to aid thepatterned sputter deposition of barrier layer 672; details thereof havebeen skipped for the sake of convenience and clarity. In one or moreembodiments, operation 804 may involve may involve curing barrier layer672 at 175° C. for 4 hours to strengthen barrier layer 672. In one ormore embodiments, operation 806 may then involve cleaning patternedflexible substrate 504 with barrier layer 672.

In one or more embodiments, operation 808 may involve depositingconductive interconnects 696 on top of barrier layer 672. In one exampleembodiment, the aforementioned deposition may be accomplished by screenprinting silver (Ag) ink or other conductive forms of ink on barrierlayer 672. Other forms of conductive interconnects 696 based onconductive paste(s) are within the scope of the exemplary embodimentsdiscussed herein. As shown in FIG. 8, a hard mask 850 may be employed toassist the selective application of conductive interconnects 696 basedon screen printing of Ag ink. In one example embodiment, hard mask 850may be a stencil.

In one or more embodiments, the screen printing of Ag ink may contributeto the continued flexibility of the thermoelectric device/module and lowcontact resistance. In one or more embodiments, operation 810 mayinvolve cleaning (e.g., using one or more of the processes discussedabove) the thermoelectric device/module/formed conductive interconnects696/barrier layer 672 and polishing conductive interconnects 696. In oneexample embodiment, the polishing may be followed by another cleaningprocess. In one or more embodiments, operation 812 may then involvecuring conductive interconnects 696 at 175° C. for 4 hours to fuse theconductive ink into solid form thereof. In one or more embodiments,conductive interconnects 696 may have a dimensional thickness less thanor equal to 25 μm.

FIG. 9 details the operations involved in encapsulating thethermoelectric device (e.g., thermoelectric module 970)/module discussedabove, according to one or more embodiments. In one or more embodiments,operation 902 may involve encapsulating the formed thermoelectric module(e.g., thermoelectric module 970)/device (with barrier layer 672 andconductive interconnects 696) with an elastomer 950 to renderflexibility thereto. In one or more embodiments, as shown in FIG. 9, theencapsulation provided by elastomer 950 may have a dimensional thicknessof less than or equal to 15 μm. In one or more embodiments, operation904 may involve doctor blading (e.g., using doctor blade 952) theencapsulation provided by elastomer 950 to finish packaging of theflexible thermoelectric device/module discussed above.

In one or more embodiments, the doctor blading may involve controllingprecision of a thickness of the encapsulation provided by elastomer 950through doctor blade 952. In one example embodiment, elastomer 950 maybe silicone. Here, said silicone may be loaded with nano-size aluminumoxide (Al₂O₃) powder to enhance thermal conductivity thereof to aid heattransfer across the thermoelectric module.

In one or more embodiments, as seen above, all operations involved infabricating the thermoelectric device/module (e.g., thermoelectricdevice 400) render said thermoelectric device/module flexible. FIG. 10shows a flexible thermoelectric device 1000 discussed herein embeddedwithin a watch strap 1002 of a watch 1004 completely wrappable around awrist 1006 of a human being 1008; flexible thermoelectric device 1000may include an array 1020 of thermoelectric modules 1020 _(1-J) (e.g.,each of which is thermoelectric device 400) discussed herein. In oneexample embodiment, flexible thermoelectric device 1000 may serve toaugment or substitute power derivation from a battery of watch 1004.FIG. 11 shows a flexible thermoelectric device 1100 discussed hereinwrapped around a heat pipe 1102; again, flexible thermoelectric device1100 may include an array 1120 of thermoelectric modules 1120 _(1-J)(e.g., each of which is thermoelectric device 400) discussed herein. Inone example embodiment, flexible thermoelectric device 1100 may beemployed to derive thermoelectric power (e.g., through array 1120) fromwaste heat from heat pipe 1102.

It should be noted that although photomask 650 is discussed above withregard to deposition of N-type thermoelectric legs 602 _(1-P) and aP-type thermoelectric legs 604 _(1-P), the aforementioned depositionmay, in one or more other embodiments, involve a hard mask 690, as shownin FIG. 6. Further, it should be noted that flexible thermoelectricdevice 400/1000/1100 may be fabricated/manufactured such that theaforementioned device is completely wrappable and bendable around asystem element (e.g., watch 1004, heat pipe 1102) that requires saidflexible thermoelectric device 400/1000/1100 to perform a thermoelectricpower generation function using the system element.

The abovementioned flexibility of thermoelectric device 400/1000/1100may be enabled through proper selection of flexible substrates (e.g.,substrate 350) and manufacturing techniques/processes that aid therein,as discussed above. Further, flexible thermoelectric device 1000/1100may be bendable 360° such that the entire device may completely wraparound the system element discussed above. Still further, in one or moreembodiments, an entire dimensional thickness of the flexiblethermoelectric module (e.g., flexible thermoelectric device 400) in apackaged form may be less than or equal to 100 μm, as shown in FIG. 9.

Last but not the least, as the dimensions involved herein are restrictedto less than or equal to 100 μm, the flexible thermoelectricdevice/module discussed above may be regarded as being thin-film based(e.g., including processes involved in fabrication thereof).

FIG. 12 shows a thermoelectric device 1200 (e.g., thermoelectric module970, also refer to the thermoelectric device of FIG. 6) discussed hereinwith elastomer encapsulation, according to one or more embodiments. Inone or more embodiments, elastomer 950 may be provided on top ofconductive interconnects 696; in certain embodiments, the encapsulationprovided through elastomer 950 may extend into physical spaces betweenadjacent N-type thermoelectric legs 602 _(1-P) and P-type thermoelectriclegs 604 _(1-P) in a direction perpendicular to a plane of substrate350.

FIG. 12 also shows Room Temperature Vulcanizing (RTV) silicone 1250(example elastomer 950) applied evenly across a surface of thethermoelectric device of FIG. 6, according to one or more embodiments.In one or more embodiments, as conductive interconnects 696 may bediscontinuous and/or the adjacent N-type thermoelectric legs 602 _(1-P)and P-type thermoelectric legs 604 _(1-P) may have physical spacestherebetween, one or more hard mask(s) (e.g., one or more stencil(s);similar to hard mask 690/850) with patterns corresponding to thethermoelectric device of FIG. 6 and the desired configuration of theencapsulation may be employed to apply said RTV silicone 1250 evenlyacross the surface of the thermoelectric device.

In one or more embodiments, following the application of RTV silicone1250, thermoelectric device 1200/RTV silicone 1250 may be cured (e.g.,curing 1204 on a hot plate 1206 or an oven 1208) at 150° C. tostrengthen the formed layer. It should be noted that, in one or moreother embodiments, RTV silicone 1250 may be mixed with a thinner (notshown; e.g., silicone fluid; other examples are within the scope of theexemplary embodiments discussed herein) to enable the resulting mixtureto provide for a less than 10 μm thickness of the formed encapsulationlayer (in general, as discussed above, the encapsulation layer may beless than or equal to 15 μm in thickness). In certain other embodiments,RTV silicone 1250 may be mixed with finely dispersed Alumina (Al₂O₃)particles (not shown) to improve thermal conductivity thereof. It shouldbe noted that the encapsulation may not solely be based on the doctorblading discussed above. Other methods to accomplish the encapsulationsuch as spin coating are within the scope of the exemplary embodimentsdiscussed herein.

It is obvious that it may be advantageous to use filler material (e.g.,Al₂O₃) of a higher thermal conductivity and/or a higher volume fractionto drastically improve thermal conductivity of the resultant mixture ofRTV silicone and said filler material without sacrificing the desiredfinal thickness (e.g., the thinner the better) of the encapsulation.Also, it is obvious that elastomer 950 may not solely be limited to RTVsilicone 1250. Varieties of market ready high thermally conductivematerials (e.g., filler material) and elastomers (or rubber) may beavailable for use in thermoelectric device 1200 and, therefore, arewithin the scope of the exemplary embodiments discussed herein.

FIG. 13 shows deposition (e.g., through sputtering) of a barrier film1302 (e.g., of Silicon Nitride (Si₃N₄), of Alumina (Al₂O₃)) prior toapplication of elastomer 950 (e.g., RTV silicone, an elastomer withthinner, an elastomer with filler material) to encapsulatethermoelectric device 1200, according to one or more embodiments. In oneor more embodiments, barrier film 1302 may be deposited (e.g., on top ofconductive interconnects 696) to reduce moisture/water vapor/oxygenpervasion into layers of thermoelectric device 1200. It is obvious thatmoisture barrier thin-films (e.g., barrier film 1302) other than thoseincluding Si₃N₄ and/or Al₂O₃ may be employed in thermoelectric device1200 prior to encapsulation thereof.

In one or more embodiments, a photomask or a hard mask (e.g., analogousto photo mask 650/hard mask 850) with patterns corresponding to barrierfilm 1302/elastomer 950 may be employed in the abovementioned depositionof barrier film 1302. In one example implementation, a 1-2 μm Si₃N₄ filmmay be sputter deposited to provide hermetic sealing to thethermoelectric layers of thermoelectric device 1200 for passivationpurposes; then, RTV silicone rubber material (example elastomer 950) maybe placed evenly thereon (e.g., based on doctor blading) to encapsulatethermoelectric device 1200; for example, the RTV silicone rubbermaterial may be provided/placed around the Si₃N₄ film. The encapsulatedthermoelectric device 1200/example elastomer 950 may then be cured at150° C. for a couple of hours to cross-link polymers therein and toprovide sealing.

It should be noted that the exemplary embodiments discussed hereinprovide for encapsulating the thin-film flexible thermoelectric device1200 into a state of permanent sealing; only output pads may be exposed.As discussed above, the encapsulation may be less than or equal to 15 μmin thickness (in one embodiment, the encapsulation may be less than 10μm in thickness). The abovementioned process of encapsulation, inconjunction with other processes involved in fabrication/manufacturingof thermoelectric device 400/thermoelectric module 970/thermoelectricdevice 1200, may enable said device to stretch or bend based on theflexibility of the final product discussed above.

FIG. 14 shows flexibility and bendability of an example thermoelectricdevice 1200 manufactured in accordance with the processes discussedherein. The aforementioned flexibility and bendability may facilitateuse of the example thermoelectric device 1200 in a variety ofapplications, some of which are discussed with reference to FIGS. 10-11.

In typical bulk thermoelectric modules, top and bottom metal traces(e.g., metal traces analogous to conductive interconnects 696 and seedlayer 550) may be separated by thermoelectric legs that are generallymore than 1 mm in height/length. Because of this significant length, thetop and bottom metal traces may not come in contact with one anotherduring soldering, thereby preventing shunting therebetween. In contrast,exemplary embodiments discussed herein provide for thermoelectric device400/thermoelectric module 970/thermoelectric device 1200 with smallN-type thermoelectric legs 602 _(1-P) and P-type thermoelectric legs 604_(1-P). Therefore, in one or more embodiments, the small thermoelectricleg height/dimension may lead to the top metal trace shunting the bottommetal trace during metal deposition, thereby producing no voltage.

In order to avoid the above shunting, in one or more embodiments, thearea of each of the N-type thermoelectric legs 602 _(1-P) and P-typethermoelectric legs 604 _(1-P) may be chosen to be larger than the areaof corresponding electrically conductive pads 506 _(1-N). In otherwords, more area corresponding to N-type thermoelectric legs 602 _(1-P)and P-type thermoelectric legs 604 _(1-P) may cover electricallyconductive pads 506 _(1-N) than required to ensure no shunting duringdeposition of conductive interconnects 696.

FIG. 15 shows extended (or, increased) area 1502 of an N-typethermoelectric leg 602 _(1-P) and another extended (or, increased) area1504 of a P-type thermoelectric leg 604 _(1-P) compared to area 1506 ofcorresponding electrically conductive pads 506 _(1-N) to ensure noshunting during deposition of conductive interconnects 696, according toone or more embodiments. In the top view, the corresponding electricallyconductive pads 506 _(1-N), the corresponding electrically conductivelead 512 _(1-P) and seed metal layer 550 underneath N-typethermoelectric leg 602 _(1-P) and P-type thermoelectric leg 604 _(1-P)are shown in dotted lines to illustrate that area 1502 and another area1504 of N-type thermoelectric leg 602 _(1-P) and P-type thermoelectricleg 604 _(1-P) respectively extend outside (or, are greater than) area1506 of the corresponding electrically conductive pads 506 _(1-N). Thisis also clearly shown in the front view of the specific element of thethermoelectric device (e.g., thermoelectric device 1200) illustrated inFIG. 15. It is obvious that the increased leg area concept extends toall sputter deposited N-type thermoelectric legs 602 _(1-P) and P-typethermoelectric legs 604 _(1-P) and corresponding electrically conductivepads 506 _(1-N) thereof in an exemplary thermoelectric device (e.g.,thermoelectric device 1200) discussed herein.

FIG. 16 shows a process flow diagram detailing the operations involvedin realizing a flexible thin-film based thermoelectric module (e.g.,thermoelectric device 1200) with a sputter deposited layer of N-type(e.g., N-type thermoelectric legs 602 _(1-P)) and P-type (e.g., P-typethermoelectric legs 604 _(1-P)) thermoelectric legs having extendedareas thereof, according to one or more embodiments.

In one or more embodiments, operation 1602 may involve forming thethin-film based thermoelectric module by sputter depositing pairs ofN-type thermoelectric legs and P-type thermoelectric legs electricallyin contact with one another on corresponding electrically conductivepads (e.g., conductive pads 506 _(1-N)) on a flexible substrate (e.g.,substrate 350) such that an area (e.g., including area 1502) of eachsputter deposited N-type thermoelectric leg and another area (e.g.,including area 1504) of each sputter deposited P-type thermoelectric legis more than an area (e.g., area 1506) of the corresponding electricallyconductive pad to allow for extension thereof outside the correspondingelectrically conductive pad. In one or more embodiments, the flexiblesubstrate may be an Al foil, a sheet of paper, teflon, plastic, asingle-sided Cu clad laminate sheet, or a double-sided Cu clad laminatesheet, and may have a dimensional thickness less than or equal to 25 μm.

In one or more embodiments, operation 1604 may involve rendering theformed thin-film based thermoelectric module flexible and less than orequal to 100 μm in dimensional thickness based on choices of fabricationprocesses with respect to layers of the formed thin-film basedthermoelectric module including the sputter deposited N-typethermoelectric legs and the P-type thermoelectric legs. In one or moreembodiments, operation 1606 may then involve encapsulating the formedthin-film based thermoelectric module with an elastomer (e.g., elastomer950) to render the flexibility thereto.

In one or more embodiments, the elastomer encapsulation may have adimensional thickness less than or equal to 15 μm. In one or moreembodiments, the flexibility may enable an array (e.g., array 1020/1120)of thin-film based thermoelectric modules, each of which is equivalentto the thin-film based thermoelectric module formed on the flexiblesubstrate with the elastomer encapsulation, to be completely wrappableand bendable around a system element from which the array of thethin-film based thermoelectric modules is configured to derivethermoelectric power.

In one or more embodiments, a layer of the formed thin-film basedthermoelectric module including the sputter deposited N-typethermoelectric legs and the P-type thermoelectric legs may have adimensional thickness less than or equal to 25 μm.

Although the present embodiments have been described with reference tospecific example embodiments, it will be evident that variousmodifications and changes may be made to these embodiments withoutdeparting from the broader spirit and scope of the various embodiments.Accordingly, the specification and drawings are to be regarded in anillustrative rather than a restrictive sense.

What is claimed is:
 1. A method of a thin-film based thermoelectricmodule, comprising: forming the thin-film based thermoelectric module bysputter depositing pairs of N-type thermoelectric legs and P-typethermoelectric legs electrically in contact with one another oncorresponding electrically conductive pads on a flexible substrate suchthat an area of each sputter deposited N-type thermoelectric leg andanother area of each sputter deposited P-type thermoelectric leg is morethan an area of the corresponding electrically conductive pad to allowfor extension thereof outside the corresponding electrically conductivepad, the flexible substrate being one of: aluminum (Al) foil, a sheet ofpaper, teflon, plastic, a single-sided copper (Cu) clad laminate sheet,and a double-sided Cu clad laminate sheet, and the flexible substratehaving a dimensional thickness less than or equal to 25 μm; renderingthe formed thin-film based thermoelectric module flexible and less thanor equal to 100 μm in dimensional thickness based on choices offabrication processes with respect to layers of the formed thin-filmbased thermoelectric module including the sputter deposited N-typethermoelectric legs and the P-type thermoelectric legs; andencapsulating the formed thin-film based thermoelectric module with anelastomer to render the flexibility thereto, the elastomer encapsulationhaving a dimensional thickness less than or equal to 15 μm, theflexibility enabling an array of thin-film based thermoelectric modules,each of which is equivalent to the thin-film based thermoelectric moduleformed on the flexible substrate with the elastomer encapsulation, to becompletely wrappable and bendable around a system element from which thearray of the thin-film based thermoelectric modules is configured toderive thermoelectric power, and a layer of the formed thin-film basedthermoelectric module including the sputter deposited N-typethermoelectric legs and the P-type thermoelectric legs having adimensional thickness less than or equal to 25 μm.
 2. The method ofclaim 1, comprising utilizing one of: a photomask and a hard mask withpatterns corresponding to one of: the N-type thermoelectric legs and theP-type thermoelectric legs to aid the sputter deposition thereof.
 3. Themethod of claim 1, further comprising printing and etching a designpattern of metal onto the flexible substrate to form the correspondingelectrically conductive pads.
 4. The method of claim 3, furthercomprising sputter depositing a barrier metal layer comprising one of:Cr, Ni and Au on top of the sputter deposited pairs of the N-typethermoelectric legs and the P-type thermoelectric legs utilizing one of:another photomask and another hard mask to further aid metallizationcontact therewith.
 5. The method of claim 4, further comprisingdepositing conductive interconnects on top of the sputter depositedbarrier metal layer utilizing a hard mask to assist selectiveapplication thereof.
 6. The method of claim 5, further comprisingdepositing the conductive interconnects through screen printingconductive forms of ink on the sputter deposited barrier metal layer. 7.The method of claim 1, comprising: depositing a moisture barrier thinfilm on the formed thin-film based thermoelectric module prior to theencapsulation thereof with the elastomer; and providing theencapsulation through the elastomer around the deposited moisturebarrier thin film.
 8. A method of a thin-film based thermoelectricmodule, comprising: forming the thin-film based thermoelectric module bysputter depositing pairs of N-type thermoelectric legs and P-typethermoelectric legs electrically in contact with one another oncorresponding electrically conductive pads on a flexible substrate suchthat an area of each sputter deposited N-type thermoelectric leg andanother area of each sputter deposited P-type thermoelectric leg is morethan an area of the corresponding electrically conductive pad to allowfor extension thereof outside the corresponding electrically conductivepad, the flexible substrate being one of: Al foil, a sheet of paper,teflon, plastic, a single-sided Cu clad laminate sheet, and adouble-sided Cu clad laminate sheet, and the flexible substrate having adimensional thickness less than or equal to 25 μm; rendering the formedthin-film based thermoelectric module flexible and less than or equal to100 μm in dimensional thickness based on choices of fabricationprocesses with respect to layers of the formed thin-film basedthermoelectric module including the sputter deposited N-typethermoelectric legs and the P-type thermoelectric legs, a layer of theformed thin-film based thermoelectric module including the sputterdeposited N-type thermoelectric legs and the P-type thermoelectric legshaving a dimensional thickness less than or equal to 25 μm;encapsulating the formed thin-film based thermoelectric module with anelastomer to render the flexibility thereto, the elastomer encapsulationhaving a dimensional thickness less than or equal to 15 μm; and wrappingand bending an array of thin-film based thermoelectric modules, each ofwhich is equivalent to the thin-film based thermoelectric module formedon the flexible substrate with the elastomer encapsulation, completelyaround a system element from which the array of the thin-film basedthermoelectric modules is configured to derive thermoelectric power inaccordance with the flexibility thereof.
 9. The method of claim 8,comprising utilizing one of: a photomask and a hard mask with patternscorresponding to one of: the N-type thermoelectric legs and the P-typethermoelectric legs to aid the sputter deposition thereof.
 10. Themethod of claim 8, further comprising printing and etching a designpattern of metal onto the flexible substrate to form the correspondingelectrically conductive pads.
 11. The method of claim 10, furthercomprising sputter depositing a barrier metal layer comprising one of:Cr, Ni and Au on top of the sputter deposited pairs of the N-typethermoelectric legs and the P-type thermoelectric legs utilizing one of:another photomask and another hard mask to further aid metallizationcontact therewith.
 12. The method of claim 11, further comprisingdepositing conductive interconnects on top of the sputter depositedbarrier metal layer utilizing a hard mask to assist selectiveapplication thereof.
 13. The method of claim 12, further comprisingdepositing the conductive interconnects through screen printingconductive forms of ink on the sputter deposited barrier metal layer.14. The method of claim 8, comprising: depositing a moisture barrierthin film on the formed thin-film based thermoelectric module prior tothe encapsulation thereof with the elastomer; and providing theencapsulation through the elastomer around the deposited moisturebarrier thin film.
 15. A method of a thin-film based thermoelectricdevice comprising: forming the thin-film based thermoelectric device outof an array of thermoelectric modules, each of which is less than orequal to 100 μm in dimensional thickness and is formed by sputterdepositing pairs of N-type thermoelectric legs and P-type thermoelectriclegs electrically in contact with one another on correspondingelectrically conductive pads on a flexible substrate such that an areaof each sputter deposited N-type thermoelectric leg and another area ofeach sputter deposited P-type thermoelectric leg is more than an area ofthe corresponding electrically conductive pad to allow for extensionthereof outside the corresponding electrically conductive pad, theflexible substrate being one of: Al foil, a sheet of paper, teflon,plastic, a single-sided Cu clad laminate sheet, and a double-sided Cuclad laminate sheet, the flexible substrate having a dimensionalthickness less than or equal to 25 μm, and a layer of the eachthermoelectric module including the sputter deposited N-typethermoelectric legs and the P-type thermoelectric legs having adimensional thickness less than or equal to 25 μm; rendering the formedthin-film based thermoelectric device flexible based on choices offabrication processes with respect to layers of the each thermoelectricmodule including the sputter deposited N-type thermoelectric legs andthe P-type thermoelectric legs; and encapsulating the eachthermoelectric module of the formed thin-film based thermoelectricdevice with an elastomer to render the flexibility thereto, theelastomer encapsulation having a dimensional thickness less than orequal to 15 μm, and the flexibility enabling the formed thin-film basedthermoelectric device to be completely wrappable and bendable around asystem element from which the formed thin-film based thermoelectricdevice is configured to derive thermoelectric power.
 16. The method ofclaim 15, comprising utilizing one of: a photomask and a hard mask withpatterns corresponding to one of: the N-type thermoelectric legs and theP-type thermoelectric legs to aid the sputter deposition thereof. 17.The method of claim 15, further comprising printing and etching a designpattern of metal onto the flexible substrate to form the correspondingelectrically conductive pads.
 18. The method of claim 17, furthercomprising sputter depositing a barrier metal layer comprising one of:Cr, Ni and Au on top of the sputter deposited pairs of the N-typethermoelectric legs and the P-type thermoelectric legs utilizing one of:another photomask and another hard mask to further aid metallizationcontact therewith.
 19. The method of claim 18, further comprisingdepositing conductive interconnects on top of the sputter depositedbarrier metal layer utilizing a hard mask to assist selectiveapplication thereof.
 20. The method of claim 19, further comprisingdepositing the conductive interconnects through screen printingconductive forms of ink on the sputter deposited barrier metal layer.